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DataSet::GetXml Method

Returns the XML representation of the data stored in the DataSet.

Namespace:  System.Data
Assembly:  System.Data (in System.Data.dll)
public:
String^ GetXml()

Return Value

Type: System::String
A string that is a representation of the data stored in the DataSet.

Calling this method is identical to calling WriteXml with XmlWriteMode set to IgnoreSchema.

GetXml returns XML as a string, and therefore requires more overhead than WriteXml to write XML to a file.

If you build a DataSet using schema inference and serialize it using XML or Web services, the column ordering may change.

The following example creates a DataSet and DataTable, adds sample data, and then displays the data in XML format.

No code example is currently available or this language may not be supported.

This sample demonstrates how to write data into an XML file from a DataSet and read data into DataSet from XML. This sample will create one dataset with two tables, use two ways to export a dataset into the XML files (WriteXml and GetXml), and use two ways (ReadXml and InferXmlSchema) to import a dataset from the XML files.

Before you compile and run the sample, you need to create four XML files in the sample directory. First, create ElementsWithAttributes.xml:

<MySchool>
  <Course CourseID="C1045" Year="2012"  Title="Calculus" Credits="4" DepartmentID="7">New</Course>
  <Course CourseID="C1061" Year="2012"  Title="Physics" Credits="4" DepartmentID="1" />
  <Department DepartmentID="1" Name="Engineering" Budget="350000" StartDate="2007-09-01T00:00:00+08:00" Administrator="2" />
  <Department DepartmentID="7" Name="Mathematics" Budget="250024" StartDate="2007-09-01T00:00:00+08:00" Administrator="3">Cancelled</Department>
</MySchool>

Next, create ElementsWithChildElementsxml.xml:

<MySchool>
  <Course>
    <CourseID>C1045</CourseID>
    <Year>2012</Year>
    <Title>Calculus</Title>
    <Credits>4</Credits>
    <DepartmentID>7</DepartmentID>
  </Course>
  <Course>
    <CourseID>C1061</CourseID>
    <Year>2012</Year>
    <Title>Physics</Title>
    <Credits>4</Credits>
    <DepartmentID>1</DepartmentID>
  </Course>
  <Course>
    <CourseID>C2021</CourseID>
    <Year>2012</Year>
    <Title>Composition</Title>
    <Credits>3</Credits>
    <DepartmentID>2</DepartmentID>
  </Course>
  <Course>
    <CourseID>C2042</CourseID>
    <Year>2012</Year>
    <Title>Literature</Title>
    <Credits>4</Credits>
    <DepartmentID>2</DepartmentID>
  </Course>
  <Department>
    <DepartmentID>1</DepartmentID>
    <Name>Engineering</Name>
    <Budget>350000</Budget>
    <StartDate>2007-09-01T00:00:00+08:00</StartDate>
    <Administrator>2</Administrator>
  </Department>
  <Department>
    <DepartmentID>2</DepartmentID>
    <Name>English</Name>
    <Budget>120000</Budget>
    <StartDate>2007-09-01T00:00:00+08:00</StartDate>
    <Administrator>6</Administrator>
  </Department>
  <Department>
    <DepartmentID>4</DepartmentID>
    <Name>Economics</Name>
    <Budget>200000</Budget>
    <StartDate>2007-09-01T00:00:00+08:00</StartDate>
    <Administrator>4</Administrator>
  </Department>
  <Department>
    <DepartmentID>7</DepartmentID>
    <Name>Mathematics</Name>
    <Budget>250024</Budget>
    <StartDate>2007-09-01T00:00:00+08:00</StartDate>
    <Administrator>3</Administrator>
  </Department>
</MySchool>

Now create ElementsWithOnlyAttributes.xml:

<MySchool>
  <Course CourseID="C1045" Year="2012"  Title="Calculus" Credits="4" DepartmentID="7" />
  <Course CourseID="C1061" Year="2012"  Title="Physics" Credits="4" DepartmentID="1" />
  <Department DepartmentID="1" Name="Engineering" Budget="350000" StartDate="2007-09-01T00:00:00+08:00" Administrator="2" />
  <Department DepartmentID="7" Name="Mathematics" Budget="250024" StartDate="2007-09-01T00:00:00+08:00" Administrator="3" />
</MySchool>

And finally, create RepeatingElements.xml:

<MySchool>
  <Course>C1045</Course>
  <Course>C1061</Course>
  <Department>Engineering</Department> 
  <Department>Mathematics</Department>
</MySchool>

Now you can compile and run the following source code. How to Store Data of DataSet into XML File has Visual Basic and C# projects for this sample.

using System;
using System.Data;
using System.IO;
using System.Text;
using System.Xml;


// Use WriteXml method to export the dataset.
static class DataTableHelper {
   public static void WriteDataSetToXML(DataSet dataset, String xmlFileName) {
      using (FileStream fsWriterStream = new FileStream(xmlFileName, FileMode.Create)) {
         using (XmlTextWriter xmlWriter = new XmlTextWriter(fsWriterStream, Encoding.Unicode)) {
            dataset.WriteXml(xmlWriter, XmlWriteMode.WriteSchema);
            Console.WriteLine("Write {0} to the File {1}.", dataset.DataSetName, xmlFileName);
            Console.WriteLine();
         }
      }
   }

   // Use GetXml method to get the XML data of the dataset and then export to the file.
   public static void GetXMLFromDataSet(DataSet dataset, String xmlFileName) {
      using (StreamWriter writer = new StreamWriter(xmlFileName)) {
         writer.WriteLine(dataset.GetXml());
         Console.WriteLine("Get Xml data from {0} and write to the File {1}.", dataset.DataSetName, xmlFileName);
         Console.WriteLine();
      }
   }


   // Use ReadXml method to import the dataset from the dataset.
   public static void ReadXmlIntoDataSet(DataSet newDataSet, String xmlFileName) {
      using (FileStream fsReaderStream = new FileStream(xmlFileName, FileMode.Open)) {
         using (XmlTextReader xmlReader = new XmlTextReader(fsReaderStream)) {
            newDataSet.ReadXml(xmlReader, XmlReadMode.ReadSchema);
         }
      }
   }


   // Display the columns and value of DataSet.
   public static void ShowDataSet(DataSet dataset) {
      foreach (DataTable table in dataset.Tables) {
         Console.WriteLine("Table {0}:", table.TableName);
         ShowDataTable(table);
      }
   }


   // Display the columns and value of DataTable.
   private static void ShowDataTable(DataTable table) {
      foreach (DataColumn col in table.Columns) {
         Console.Write("{0,-14}", col.ColumnName);
      }
      Console.WriteLine("{0,-14}", "");

      foreach (DataRow row in table.Rows) {
         if (row.RowState == DataRowState.Deleted) {
            foreach (DataColumn col in table.Columns) {
               if (col.DataType.Equals(typeof(DateTime))) {
                  Console.Write("{0,-14:d}", row[col, DataRowVersion.Original]);
               }
               else if (col.DataType.Equals(typeof(Decimal))) {
                  Console.Write("{0,-14:C}", row[col, DataRowVersion.Original]);
               }
               else {
                  Console.Write("{0,-14}", row[col, DataRowVersion.Original]);
               }
            }
         }
         else {
            foreach (DataColumn col in table.Columns) {
               if (col.DataType.Equals(typeof(DateTime))) {
                  Console.Write("{0,-14:d}", row[col]);
               }
               else if (col.DataType.Equals(typeof(Decimal))) {
                  Console.Write("{0,-14:C}", row[col]);
               }
               else {
                  Console.Write("{0,-14}", row[col]);
               }
            }
         }
         Console.WriteLine("{0,-14}", "");
      }
   }


   // Display the columns of DataSet.
   public static void ShowDataSetSchema(DataSet dataSet) {
      Console.WriteLine("{0} contains the following tables:", dataSet.DataSetName);
      foreach (DataTable table in dataSet.Tables) {
         Console.WriteLine("   Table {0} contains the following columns:", table.TableName);
         ShowDataTableSchema(table);
      }
   }


   // Display the columns of DataTable
   private static void ShowDataTableSchema(DataTable table) {
      String columnString = "";
      foreach (DataColumn col in table.Columns) {
         columnString += col.ColumnName + "   ";
      }
      Console.WriteLine(columnString);
   }
}




class Program {
   static void Main(string[] args) {
      // Create the DataSet
      DataSet school = new DataSet("MySchool");
      DataTable course = CreateCourse();
      DataTable department = CreateDepartment();
      school.Tables.Add(course);
      school.Tables.Add(department);

      // Define the constraint between the tables.
      ForeignKeyConstraint courseDepartFK = new ForeignKeyConstraint("CourseDepartFK", department.Columns["DepartmentID"], course.Columns["DepartmentID"]);
      courseDepartFK.DeleteRule = Rule.Cascade;
      courseDepartFK.UpdateRule = Rule.Cascade;
      courseDepartFK.AcceptRejectRule = AcceptRejectRule.None;
      course.Constraints.Add(courseDepartFK);

      InsertDepartments(department);
      InsertCourses(course);

      // Export the dataset to the XML file.
      Console.WriteLine("Data of the whole DataSet {0}", school.DataSetName);
      DataTableHelper.ShowDataSet(school);

      String xmlWithSchemaFileName = "WriterXMLWithSchema.xml";
      String xmlGetDataFileName = "GetXML.xml";

      // Use two ways to export the dataset to the Xml file.
      DataTableHelper.WriteDataSetToXML(school, xmlWithSchemaFileName);
      DataTableHelper.GetXMLFromDataSet(school, xmlGetDataFileName);


      // Import the dataset from the XML file.
      // Use two ways to import the dataset from the Xml file.
      Console.WriteLine("Read Xml document into a new DataSet:");
      DataSet newSchool = new DataSet("NewSchool");
      DataTableHelper.ReadXmlIntoDataSet(newSchool, xmlWithSchemaFileName);
      DataTableHelper.ShowDataSetSchema(newSchool);
      Console.WriteLine();

      Console.WriteLine("Infer a schema for a DataSet from an XML document:");
      InferDataSetSchemaFromXml();

      Console.WriteLine("Press any key to exit.");
      Console.ReadKey();
   }

   static DataTable CreateCourse() {
      DataTable course = new DataTable("Course");
      DataColumn[] cols ={
                              new DataColumn("CourseID",typeof(String)),
                              new DataColumn("Year",typeof(Int32)),
                              new DataColumn("Title",typeof(String)),
                              new DataColumn("Credits",typeof(Int32)),
                              new DataColumn("DepartmentID",typeof(Int32))};
      course.Columns.AddRange(cols);

      course.PrimaryKey = new DataColumn[] { course.Columns["CourseID"], course.Columns["Year"] };

      return course;
   }

   static DataTable CreateDepartment() {
      DataTable department = new DataTable("Department");
      DataColumn[] cols = { 
                                new DataColumn("DepartmentID", typeof(Int32)),
                                new DataColumn("Name",typeof(String)),
                                new DataColumn("Budget",typeof(Decimal)),
                                new DataColumn("StartDate",typeof(DateTime)),
                                new DataColumn("Administrator",typeof(Int32))};
      department.Columns.AddRange(cols);

      department.PrimaryKey = new DataColumn[] { department.Columns["DepartmentID"] };

      return department;
   }

   static void InsertDepartments(DataTable department) {
      Object[] rows = { 
                            new Object[]{1,"Engineering",350000.00,new DateTime(2007,9,1),2},
                            new Object[]{2,"English",120000.00,new DateTime(2007,9,1),6},
                            new Object[]{4,"Economics",200000.00,new DateTime(2007,9,1),4},
                            new Object[]{7,"Mathematics",250024.00,new DateTime(2007,9,1),3}};

      foreach (Object[] row in rows) {
         department.Rows.Add(row);
      }
   }

   static void InsertCourses(DataTable course) {
      Object[] rows ={
                               new Object[]{"C1045",2012,"Calculus",4,7},
                               new Object[]{"C1061",2012,"Physics",4,1},
                               new Object[]{"C2021",2012,"Composition",3,2},
                               new Object[]{"C2042",2012,"Literature",4,2}};

      foreach (Object[] row in rows) {
         course.Rows.Add(row);
      }
   }

   // Display the results of inferring schema from four types of XML structures
   private static void InferDataSetSchemaFromXml() {
      String[] xmlFileNames = { 

                                    @"ElementsWithOnlyAttributes.xml", 
                                    @"ElementsWithAttributes.xml",
                                    @"RepeatingElements.xml", 
                                    @"ElementsWithChildElements.xml" };


      foreach (String xmlFileName in xmlFileNames) {
         Console.WriteLine("Result of {0}", Path.GetFileNameWithoutExtension(xmlFileName));
         DataSet newSchool = new DataSet();
         newSchool.InferXmlSchema(xmlFileName, null);
         DataTableHelper.ShowDataSetSchema(newSchool);
         Console.WriteLine();
      }
   }
}

.NET Framework

Supported in: 4.5.1, 4.5, 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows Phone 8.1, Windows Phone 8, Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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